BRAKE PEDAL EFFORT CHANGE NEW VACUUM SUPPLY KIT RELEASED

SUBJECT: BRAKE PEDAL EFFORT (CHANGE VACUUM SUPPLY SYSTEM FROM ENGINE TO THE BOOSTER/NEW KIT)

VEHICLES AFFECTED: 1991 "B" CAR (POLICE OPTION)

Condition:

--------- Some drivers of police vehicles may comment on brake pedal effort upon quick reapplies of the brakes following a wide-open throttle (WOT) or repeated wide-open throttle accelerations.

Correction:

---------- Increased vacuum recovery may be assisted by changing the vacuum supply system from the engine to the booster. A new booster supply system has been released for SOP, 1992. A service kit is available from CANSPO for 1991 vehicles, P/N #10216003.

This Booster Kit, Power Brake Vacuum, P/N #10216003 contains the following parts:

1. Fitting (to engine) - P/N 14102142

2. Tube - P/N 10209899

3. Screw (tubing to throttle bracket) - P/N 11513569

4. Hose (tube to check valve) - P/N 10209774

5. Vacuum Check Valve Kit (includes grommet) - P/N 18012017A

Service Procedure:

1. Remove Air Cleaner.

2. Remove and discard the following items:

A. Vacuum Check Valve and Grommet

B. Filter

C. Hose

D. Tubing

E. Engine Vacuum Fitting

3. Install parts from kit, P/N #10216003, refer to Illustration 1.

A. Use pipe thread sealer before installing the vacuum fitting into the TBI adapter. Torque to 12 N.m (110 inch pounds ).

B. Position vacuum tube assembly as shown in Illustration and finger tighten onto the fitting. Pivot tube assembly to position shown in Illustration view la and prick punch the bracket to locate position of the attaching hole. Drill 1/8 inch hole through throttle bracket.

IMPORTANT: --------- Care must be taken when drilling hole to insure that the transmission detent cable is not damaged.

C. Install screw and torque to 2.8 N.m (25 inch pounds

D. Torque the tube nut to 12 N.m (110 inch pounds ).

E. Install check valve into the end of the hose with the sharper bend. At this point briefly position the check valve to the booster to an approximate 11:00 position and install as in Figure 1. It may be necessary to hold the tube with the left hand so the tube will not bend when installing the hose to the tube.

F. Install the new grommet and vacuum check valve into booster.

4. Reinstall Air Cleaner.

IMPORTANT: --------- Start engine and check for proper braking action before road testing.

For vehicles repaired under warranty use:

Labour Time : 0.5 Hours

General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.